Endoluminal stents and methods of delivery

ABSTRACT

An endoluminal stent and associated methods for placing the endoluminal stent in a lumen of a trachea of a patient. The stent includes an elongate framework having a first open end, a second open end opposite the first open end, and a lumen extending from the first open end to the second open end. The elongate framework includes a first edge extending from the first open end to the second open end, a second edge extending from the first open end to the second open end, and an opening between the first edge and the second edge extending from the first open end to the second open end such that the stent has a C-shaped cross-section. The stent may be implanted in a trachea with the opening positioned along a posterior wall of the trachea adjacent the trachealis muscle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/725,655, filed May 29, 2015, which claims priority to U.S.Provisional Application No. 62/005,314, filed May 30, 2014, the entiredisclosures of which are herein incorporated by reference.

TECHNICAL FIELD

Some embodiments relate to medical devices, and methods formanufacturing and using the same. More particularly, the presentdisclosure relates to devices such as stents for supporting bodystructures such as tracheae and/or preventing or resisting collapsing ofbody structures such as tracheae.

BACKGROUND

In general, the human body includes various lumens, such as a trachea,arteries, blood vessels, as well as urinary, biliary, esophageal orrenal tracts, etc. These lumens sometimes become occluded or weakened,or otherwise in need of structural support. For example, the body lumencan be constricted by a tumor, occluded by plaque, or weakened by ananeurysm. For instance, tracheobronchomalacia or TBM is a conditioncharacterized by flaccidity of the cartilage that supports the trachea.This leads to tracheal collapse which in some instances may extendfurther to the bronchi. TBM may cause discomfort in swallowing,coughing, and breathing to the patient. However, such a condition of thepatient can be treated with a medical endoprosthesis to help support thetrachea.

Endoprostheses have been developed that may be implanted in a passagewayor lumen in the body. In general, such endoprostheses are tubularmembers with a circular cross-section, examples of which include stents,stent grafts, covered stents, etc. However, such endoprostheses may notbe suitable for lumens such as tracheae having non-circularcross-sections, such as a D-shaped cross-section, which requirescontinued functionality of the trachealis muscle to permit the flow ofmucus therethrough, for example.

For instance, the trachea, which lies adjacent to esophagus, has a flatposterior wall which may be pressed by a circular stent, impeding thefunctionality of the trachealis muscle. In some other instances,existing stents may not be suitable for deployment in branching airways,as the stenting may block side branching airways in the bronchi, forexample. In addition, the stents may not allow mucus clearing. Hence,there may exist a need of stents or endoprostheses that may providedesired luminal support while preserving other functionality of the bodylumen.

SUMMARY

One illustrative embodiment is an endoluminal stent. The endoluminalstent includes an elongate framework. The elongate framework has a firstopen end, a second open end and opposite the first open end, and a lumenextending from the first open end to the second open end. The elongateframework includes a first edge extending from the first open end to thesecond open end, a second edge extending from the first open end to thesecond open end, and an opening between the first edge and the secondedge. The opening can extend continuously from the first open end to thesecond open end.

Another illustrative embodiment is an endoluminal stent. The endoluminalstent includes an elongate framework. The elongate framework has a firstopen end, a second open end opposite the first open end, and a lumenextending along a longitudinal axis from the first open end to thesecond open end. The elongate framework has a C-shaped cross section ina plane perpendicular to the longitudinal axis.

Another illustrative embodiment is a method of placing a stent in alumen of a trachea. The method can include inserting a stent in a lumenof a trachea. The stent can include an elongate framework having a firstopen end, a second open end opposite the first open end, a lumenextending along a longitudinal axis from the first open end to thesecond open end, and an opening between opposing longitudinal edges ofthe elongate framework. The opening can extend continuously from thefirst open end to the second open end. The method can include orientingthe stent in the lumen of the trachea such that the opening ispositioned along a posterior wall of the trachea adjacent a trachealismuscle.

Yet another illustrative embodiment is an endoluminal stent. Theendoluminal stent includes an elongate framework. The elongate frameworkhas a first open end, a second open end opposite the first open end, anda lumen extending from the first open end to the second open end. Theelongate framework includes a first edge extending from the first openend to the second open end, a second edge extending from the first openend to the second open end, and an opening extending continuously fromthe first open end to the second open end.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present disclosure.The Figures, and Detailed Description, which follow, more particularlyexemplify these embodiments, but are also intended as exemplary and notlimiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary endoluminal stent, inaccordance with some embodiments of the present disclosure;

FIG. 2A is a cross-sectional view of the exemplary endoluminal stent ofFIG. 1;

FIG. 2B is a top view of the exemplary endoluminal stent implanted in atrachea of a patient;

FIG. 3 is a cross-sectional view of an exemplary endoluminal stent witha covering;

FIG. 4A illustrates another embodiment of an exemplary endoluminalstent, in accordance with some embodiments of the present disclosure;

FIG. 4B is a top view of the exemplary endoluminal stent of FIG. 4Aimplanted in a trachea of a patient;

FIG. 4C is a top view of the exemplary endoluminal stent of FIG. 4Aimplanted in a trachea of a patient during coughing;

FIGS. 5A and 5B are cross-sectional views of the exemplary endoluminalstent of FIG. 4A implanted in a trachea where first and second edgeregions are drawn toward one another;

FIG. 6 illustrates a perspective view of implantation of an exemplaryendoluminal stent implanted in bronchi;

FIG. 7 illustrates an exemplary delivery system for placing an exemplarystent in a body lumen, such as the lumen of a trachea;

FIG. 7A is a cross-sectional view taken along line 7A-7A of FIG. 7illustrating an exemplary endoluminal stent in a delivery configuration.

DETAILED DESCRIPTION

Definitions of certain terms are provided below and shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same or substantiallythe same function or result). In many instances, the terms “about” mayinclude numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include or otherwise refer to singular aswell as plural referents, unless the content clearly dictates otherwise.As used in this specification and the appended claims, the term “or” isgenerally employed to include “and/or,” unless the content clearlydictates otherwise.

The following detailed description should be read with reference to thedrawings, in which similar elements in different drawings are identifiedwith the same reference numbers. The drawings, which are not necessarilyto scale, depict illustrative embodiments and are not intended to limitthe scope of the disclosure.

FIG. 1 is a perspective view of an exemplary endoluminal stent 100. Theendoluminal stent 100 may include an elongate framework 102. In someinstances, the framework 102 may include a plurality of interstices 103formed between adjacent segments of the framework 102. For example, insome instances the framework 102 may include a number of interconnectedstruts 104 defining a plurality of interstices 103 therebetween.

The framework 102 may include a first open end 106, a second open end108 opposite the first open end 106, and a lumen 110 extending betweenthe first open end 106 and the second open end 108. In some embodiments,the length of the framework 102 may depend upon the length of the lumenin which the framework 102 may be inserted. The framework 102 mayinclude a first edge 112, a second edge 114, each extending from thefirst open end 106 to the second open end 108, and an opening 116between the first edge 112 and the second edge 114 that extendscontinuously from the first open end 106 to the second open end 108. Insome instance, the framework 102 may include one or more, or a pluralityof bridge members extending across the opening 116 between the firstedge 112 and the second edge 114. The first edge 112 may be asubstantially straight edge parallel to the longitudinal axis A.However, it is understood that the first edge 112 may be angled orcurved, if desired. Similarly, the second edge 114 may be asubstantially straight edge extending parallel to the longitudinal axisA. However, it is understood that the second edge 114 may be angled orcurved, if desired. The first edge 112 may extend generally parallel tothe second edge 114, in some instances, or the first edge 112 may benonparallel to the second edge 114, if desired.

The opening 116 may be sized to align with the size of a posterior wallof a trachea. For example, the width of the opening may be about thewidth of the posterior wall of a trachea in some instances.

The framework 102 may be flexible such that size of the opening 116 canbe adjusted by the application of force on the framework 102 by the useror when the endoluminal stent 100 comes in contact with the lumen walls(not shown). In some embodiments, the opening 116 can be contracted bymoving the first and second edges 112, 114 past each other, for example,in an overlapping or spiral pattern. An example of such a configurationthat may have a small delivery footprint will be discussed in detailwith reference to FIG. 7A.

In some embodiments, the framework 102 may form an open structure. Asshown in FIG. 1, the struts 104 may be formed as a unitary structurefrom a single piece of material, such as a tubular member or a flatsheet of material. In some instances, the struts 104 may be laser cutfrom a tubular member or flat sheet of material. In other instances, thestruts 104 may be formed of separate pieces (e.g., filaments) andattached to each other using known mechanisms such as melting, welding,etc., thereby forming a circumferential pattern around a longitudinalaxis A to form the circumferential framework 102, or the separate piecesmay be interwoven, braided, or otherwise arranged to form the framework102. Voids between the struts or members 104 may form interstices 103.

In some instances, the framework 102 may include different patterns ofstruts 104 and/or interstices 103 along different portions of the lengthof the framework 102. For example, the size, shape, spacing, etc. of theinterstices 103 may be varied along the length of the framework 102,such that a first (e.g., proximal) portion of the framework 102 may havea first configuration of interstices 103 (e.g., size, shape, spacing,etc.) and a second (e.g., distal) portion of the framework 102 may havea second configuration of interstices 103 (e.g., size, shape, spacing,etc.), different than the first configuration. In another example, abraided configuration of the stent 100 may include a first braid patternalong a proximal portion of the framework 102 and a second braid patternalong a distal portion of the framework 102, different from the firstbraid pattern, resulting in a variation of the interstice 103. Varyingthe pattern of struts 104 and/or interstices 103 may vary the radialforce and/or flexibility of the framework 102 along the length of thestent 100.

In some instance, the interstices 103 may allow tissue ingrowth aroundthe endoluminal stent 100 through the interstices 103. In otherinstances, the stent 100 may include a covering (e.g., a coating) acrossthe interstices 103 to prevent tissue ingrowth. It is understood thatthe struts 104 in the framework 102 may have any desirable shape,permitting the framework 102 to expand and/or contract, as desired. Insome embodiments, the number or arrangement of the struts 104 may beselected based on the rigidity or porosity of the framework 102. Forexample, the elongate framework 102 may include two, three, four, five,six, seven, eight, nine, ten, or more different patterns of struts 104symmetrically or asymmetrically arranged around the circumference of theframework 102, as desired.

The framework 102 may be formed using any desired material, such as ametallic material or a polymeric material. In some instances, theinterconnected struts 104 forming the framework 102 may be formed or cutfrom a thin metal or polymeric sheet with different patterns and rolledinto a tubular configuration. In other embodiments, the struts 104forming the framework 102 may be formed or cut from a metal or polymerictubular member, with an elongate cut through the sidewall along one sideto form a C-shaped framework 102. In some embodiments, the pattern ofthe struts 104 with the interstices 103 may facilitate radialcompression or expansion (i.e., change in diameter) and/or elongation(i.e., change in length) of the framework 102. Thus, the framework 102may be able to be compressed or expanded to fit the anatomy of the bodylumen where it is implanted. The framework 102 of the stent 100 may beself-expandable or expandable by the application of an external appliedforce, such as a balloon positioned within the framework 102 exerting aradially outward force onto the framework 102.

In some embodiments, the framework 102 may be formed using metallicmaterial, such as stainless steel, tungsten, etc. In some instances themetallic material may be a super elastic alloy or a shape memory alloy,such as nitinol. The framework 102 may be formed by cutting a nitinoltube or a flat sheet by a laser or another technique that is known inthe art. The framework 102 may then be formed into a C-shape by knownmethods, thereby forming a C-shaped endoluminal stent. In some otherembodiments, the framework 102 may be formed using any suitable method,such as, but not limited to, over molding, injection molding, dipmolding, and so forth. In some other embodiments, the framework 102 maybe formed using any biocompatible polymer, such as polyurethane,polyamide, silicone, or other desired polymeric material. In someinstances, the framework 102 or other portion of the stent 100 mayinclude one or more radiopaque elements attached to the stent 100, maybe formed at least in part of a radiopaque material, and/or may includea radiopaque material incorporated into filaments or struts 104 to aidin visualization of the stent 100 within the anatomy of a patient.

The framework 102 may have a C-shaped cross-section in a planeperpendicular to the longitudinal axis A to more closely conform to thecross-sectional shape of a trachea. An exemplary C-shaped cross-sectionof the endoluminal stent of FIG. 1 in a relaxed or unrestrained state isshown in FIG. 2A. As shown in FIG. 2A, the framework 102 may include afirst edge region 118 that includes the first edge 112 and thesurrounding area, and a second edge region 120 that includes the secondedge 114 and the surrounding area. Further, the framework 102 mayinclude an intermediate region 122 between the first edge region 118 andthe second edge region 120. The framework 102 (at the intermediateregion 122) may have a radius of curvature R in a relaxed orunrestrained state. The radius of curvature R may be equal to or greaterthan the radius of the trachea of a patient, for example.

In some embodiments, the radius R of the framework 102 may be such thatthe framework 102 may be inserted in lumens of various sizes andgeometry. For example, the opening 116 of the endoluminal stent 100 maybe reduced by, for example, application of force to constrict thecurvature of the framework 102 to a radius of curvature R′ to fit withinthe trachea 200 of a patient, as shown in FIG. 2B. Thus, when implanted,the framework 102 may have a radius of curvature R′ in a constricted orrestrained state less than the radius of curvature R in an unrestrainedstate.

The trachea 200 is a passage that enables air to travel between the oraland nasal cavities into bronchi, in order to reach the lungs duringbreathing. The trachea 200 may include an anterior wall 204 and aposterior wall 206. The trachea 200 may have an elongated D-shapedcross-section with the flat posterior wall 206. Several C-shaped bars ofthe hyaline cartilage 202 prevent the trachea 200 from collapsing. Theposterior wall 206 includes a trachealis muscle 208 that constricts intothe lumen 214 of the trachea 200 to narrow the airway in order expel airfrom the trachea during a cough, and the anterior wall 204 includescartilage rings. The trachea 200 is oriented anterior to the esophagus212, with the trachealis muscle 208 positioned between the lumen 214 ofthe trachea and the esophagus 212.

As discussed above, in some instances the trachea 200 may be weakened bya disease, such as trachaeobronchomalacia (TBM), impinged by a tumor,injured by trauma, or otherwise impaired, and thus may require asupport. For treatment, the endoluminal stent 100 may be inserted into alumen 214 of the trachea 200 such that the intermediate region 122 ofthe endoluminal stent 100 may come in contact with the anterior wall 204of the trachea 200 and the opening 116 between the first edge 112 andthe second edge 114 may be positioned along the posterior wall 206adjacent the trachealis muscle 208. Hence, the anterior wall 204 may becovered by the endoluminal stent 100 while the posterior wall 206 may beuncovered, thereby allowing the uncovered area to allow mucus clearing.

In some embodiments, the radius R of the endoluminal stent 100 may beequal to the radius r of the trachea 200 to provide the sufficientradial force and structure to the trachea 200. In some embodiments, theradius R of the endoluminal stent 100 may be larger than or smaller thanthe radius r of the trachea 200 to provide the sufficient radial forceand support to the structure of the trachea 200.

FIG. 3 is a cross-sectional view of the exemplary endoluminal stent 100with a covering layer 300. In some instances, the covering layer 300 maybe configured to be disposed on the endoluminal stent 100 (e.g., on theframework 102) so that structures of the trachea may be maintained andtissue formation on the trachea 200 may be prevented. In some instances,the covering layer 300 may cover the framework 102 of the endoluminalstent 100 except for the open area of its C-shape (i.e., the opening116). In other instances, a portion of the covering layer 300 may extendacross the opening 116 of the framework 102 from the first edge 112 tothe second edge 114. As shown in FIG. 3, the covering layer 300 mayinclude a first portion 302 and a second portion 304. The first portion302 may cover the struts 104 (the first edge region 118, the second edgeregion 120, and the intermediate region 122), as well as the interstices103 of the framework 102. The second portion 304 may extend across theopening 116 of the framework 102, and thus may be positioned adjacentthe posterior wall 206 of the trachea 200, thereby covering theendoluminal stent 100 fully. In some instances, the second portion 304of the covering layer 300 extending across the opening 116 may be planar(e.g., may extend straight from the first edge 112 to the second edge114). However, in some embodiments, the covering layer 300 may coveronly the struts 104 and the interstices 103, if desired. As shown inFIG. 3, the first portion 302 may have thickness T1 and the secondportion 304 may have thickness T2 different than the thickness T1. Forexample, the thickness T1 may be greater than or less than the thicknessT2. In some embodiments, the second portion 304 may be thicker in theopening 116 of the C-shape, thereby resisting tumor ingrowth on theposterior wall 206 of the trachea 200.

In some embodiments, the covering layer 300 may be flexible providingcomfort in swallowing and coughing to the patient. For example, as shownin phantom lines in FIG. 3, the covering layer 300 may deflect into thelumen of the stent 100 as the trachealis muscle contracts into the lumenof the trachea 200 during a cough.

In some embodiments, variation in thickness of the covering 300 may beachieved by any desired method. Examples of such methods may include butare not limited to spray coating, dip coating, or a combination of dipand spray coating, and so on.

In some embodiments, the covering 300 may be formed from a biocompatiblematerial. Examples of such materials may include but are not limited topolymers such as silicone, polyvinylchloride, polyurethane, high-densitypolyethylene (HDPE), low-density polyethylene (LDPE), as well as otherbiocompatible polymer materials.

FIG. 4A is a cross-sectional view of another embodiment of an exemplaryendoluminal stent 400. The structure of the endoluminal stent 400 may besimilar to the endoluminal stent 100 except described below herein. Theendoluminal stent 400 may include an elongate framework 402 including afirst edge 412 extending from the first open end to the second open end,a second edge 414 extending from the first open end to the second openend, and an opening 416 (see FIG. 4B) between the first edge 412 and thesecond edge 414 extending from the first open end to the second open endsuch that the stent 400 has a C-shaped cross-section.

The C-shaped cross-section of the framework 402 of the endoluminal stent400 may include a first curled end region 424, a second curled endregion 426, and a central arcuate portion 428 extending between thefirst and second curled end regions 424, 426. The central arcuateportion 428 may have a primary radius of curvature R₁ about alongitudinal axis A extending from the first open end of the endoluminalstent 400 to the second open end of the endoluminal stent 400. The firstcurled end region 424 may have a first secondary radius of curvature R₂about a longitudinal axis B extending through the lumen of the framework402. The second curled end region 426 may have a second secondary radiusof curvature R₃ about a longitudinal axis C extending through the lumenof the framework 402. The longitudinal axes B and C may be parallel tothe longitudinal axis A, if desired. In some embodiments, the radii ofcurvatures R₂, R₃ of the first and second curled end regions 424, 426may be less than the radius of curvature R₁ of the central arcuateportion 428. Hence, the first and second curled end regions 424, 426 maybe curled or turned inward toward the center of the endoluminal stent400. In some instances, the radii of curvature R₂, R₃ at the edges 412,414 may approximate the radius between the cartilage rings andtrachealis muscle of the trachea during a cough (see FIG. 4C) to resistcollapse and further prevent granulation tissue formation.

As shown in FIG. 4B, the endoluminal stent 400 may be placed in thetrachea 200 in a similar way to that of the endoluminal stent 100. Forexample, the endoluminal stent 400 may be implanted in the trachea 200with the opening 416 between the edges 412, 414 positioned along theposterior wall 206 of the trachea 200 adjacent the trachealis muscle208. In this orientation, the endoluminal stent 400 may cover theanterior wall 204 of the trachea 200 while the posterior wall 206 of thetrachea 200 may remain uncovered.

During coughing, for example, the trachealis muscle 208 may contractinto the lumen of the trachea 200 such that the uncovered posterior wall206 of the trachea 200 may deflect towards the lumen 410 of theendoluminal stent 400. Thus, a portion of the posterior wall 206 maydeflect towards the lumen 410 and follow the curvature of the first andsecond curled end regions 424, 426, as shown in FIG. 4C. Hence, theradii of curvature R₂, R₃ at the first and second curled end regions424, 426 may be designed in a way that the radii at the edges 412, 414may match or approximate the radius of the trachea 200 between thecartilage rings and the trachealis muscle 208 during a cough to resistcollapse and further prevent granulation tissue formation.

If it is desired to remove or reposition the endoluminal stent 400, thefirst and second curled end regions 424, 426 may be drawn toward oneanother with a medical device (e.g., forceps) to constrain the stent400. The first and second curled end regions 424, 426 may provide easyfeatures to grab for removal of the endoluminal stent 400 via forceps orgrasping tool (not shown). The first and second curled end regions 424,426 may be grabbed with the forceps, followed by twisting to reduceouter diameter and then may be pulled out, for example.

In some embodiments, the first and second curled end regions 424, 426may provide additional rigidity to the endoluminal stent 400 and resisttumors or other obstructions in the trachea. For example, as shown inFIG. 5A, the first and second curled end regions 424, 426 may have radiiof curvature that brings the end regions 424, 426 close to one anotherwhile maintaining a gap or opening 416 therebetween. As shown in 5B, ifthe trachea 200 is compressed by growth of a tumor, the first and secondcurled end regions 424, 426 may come in contact with each other andthereafter prevent further collapse of the stent 400 and thus provideadditional resistance against the tumor. Such contact between the firstand second curled end regions 424, 426 may provide a strong radialresistance force but also allow for a fluid drainage channel between theendoluminal stent 400 and the lumen wall of the trachea 200.

FIG. 6 illustrates a perspective view of an exemplary endoluminal stent600 near a luminal branch, such as a branch region of bronchi 650.However, in some embodiments, the endoluminal stent 600 may be employedin a bifurcation of a vessel, bile duct, hepatic duct, or otherbifurcations. The endoluminal stent 600 may be similar to that of theendoluminal stent 100 or the endoluminal stent 400. Insertion of theendoluminal stent 600 in a lumen 655 of a bronchi (or other lumen) mayallow stenting without blockage of the side-branching lumen 660. Forexample, the opening 616 between the first edge 612 and the second edge614 may be positioned toward the side-branching lumen 660, such that theopening 616 opens into the side-branching lumen 660. In someembodiments, the insertion may also allow fluid (e.g., air) to passthrough the side branching lumen 660 from the main lumen 655.

FIG. 7 illustrates a delivery system 700 to deliver an exemplaryendoluminal stent in a lumen of a trachea. The delivery system 700 mayinclude an outer member or sheath 702 and an inner member or pusher 704.The sheath 702 may be an elongated member having a proximal end 706, adistal end 708, and a lumen 725 extending from the proximal end 706 tothe distal end 708. The sheath 702 may be configured to receive anendoluminal stent 750 in a collapsed state and deliver the endoluminalstent 750 at a target location. The endoluminal stent 750 may be anendoluminal stent as described above.

The endoluminal stent 750 may be loaded into the lumen 725 by anydesired means. For example, the endoluminal stent 750 may be introducedin the lumen 725 from the distal end 708 of the sheath 702. In someinstances, the structure of the endoluminal stent 750 may be similar tothe endoluminal stent 100 or 400, if desired.

Further, the delivery system 700 may include an inner member or pusher704 extending through the lumen 725 of the sheath 702. The pusher 704may be actuated relative to the sheath 702 to create a push-pullmechanism. The pusher 704 may include an elongate shaft 708 having ahandle 720 at a proximal end 712 thereof and an engagement member 710 ata distal end 714 thereof configured to engage the endoluminal stent 750.The engagement member 710 may be configured to deploy the endoluminalstent 750 upon actuation of the shaft 708 relative to the sheath 702.The handle 720 may be disposed at the proximal end 712 of the shaft 708and may be configured to be held by an operator to actuate the pusher704. Once the physician actuates the pusher 704, the engagement member710 may push the endoluminal stent 750 distally out of the lumen 725thereby deploying the endoluminal stent 750.

In some instances the delivery system 700 may include a deliverymechanism including members configured to engage the curved edges of thestent 750 and pull the curved edges of the stent 750 together to reducethe profile of the stent 750.

FIG. 7A illustrates a cross-sectional view of the sheath 702 includingthe endoluminal stent 750 taken along line 7A-7A of FIG. 7. Theendoluminal stent 750 may be placed in the sheath 702 in a collapsedstate. For example, in some embodiments, the endoluminal stent 750 maybe curled and compressed down to a small diameter for delivery into atrachea, vessel, or other lumen in which the endoluminal stent 750 maybe placed. Since the endoluminal stent 750 may have a first edge 712extending longitudinally from a first end to a second end of theendoluminal stent 750, and a second edge 714 extending longitudinallyfrom the first end to the second end of the endoluminal stent 750, thestent 750 may be rolled up into a tight spiral to reduce the deliverydiameter of the stent 750, for example. Thus, the first edge 712 mayoverlap with the second edge 714 in a constricted, deliveryconfiguration within the lumen 725 of the delivery system 700.

A method of placing an exemplary endoluminal stent in a lumen of thetrachea may include a number of consecutive, non-consecutive,simultaneous, non-simultaneous, or alternative steps. The method mayinclude inserting the endoluminal stent into the lumen of the trachea.The method may further include orienting the endoluminal stent in thelumen of the trachea. The endoluminal stent may be oriented such thatthe opening of the endoluminal stent may be positioned along a posteriorwall of the trachea adjacent a trachealis muscle.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps, without exceeding the scope ofthe disclosure. This may include, to the extent that it is appropriate,the use of any of the features of one exemplary embodiment in otherembodiments. The disclosure's scope is, of course, defined in thelanguage in which the appended claims are expressed.

ADDITIONAL EXAMPLES

A first example includes an endoluminal stent comprising an elongateframework. The elongate framework has a first open end, a second openend opposite the first open end, and a lumen extending from the firstopen end to the second open end. The elongate framework also includes afirst edge extending from the first open end to the second open end, asecond edge extending from the first open end to the second open end,and an opening between the first edge and the second edge. The openingextends continuously from the first open end to the second open end.

Additionally or alternatively, in a second example, the elongateframework is formed of a plurality of interconnected struts defininginterstices therebetween.

Additionally or alternatively, in a third example, the elongateframework includes a first edge region proximate the first edgeextending from the first open end to the second open end, a second edgeregion proximate the second edge extending from the first open end tothe second open end, and an intermediate region between the first andsecond edge regions extending from the first open end to the second openend. The intermediate region has a primary radius of curvature about aprimary longitudinal axis extending through the lumen, the first edgeregion has a first secondary radius of curvature about a first secondarylongitudinal axis extending through the lumen, and the second edgeregion has a second secondary radius of curvature about a secondsecondary longitudinal axis extending through the lumen. The firstsecondary radius of curvature and the second secondary radius ofcurvature are less than the primary radius of curvature.

Additionally or alternatively, in a fourth example, the endoluminalstent is configured to be positioned in a trachea with the openingoriented toward a posterior wall of the trachea.

Additionally or alternatively, in a fifth example, the first and secondedges are configured to be drawn toward one another with a medicaldevice to remove the endoluminal stent from a body lumen.

Additionally or alternatively, in a sixth example, the first and secondedge regions are configured to abut one another to resist radialcontraction of the endoluminal stent in a body lumen.

Additionally or alternatively, in a seventh example, the endoluminalstent includes a covering layer covering at least a portion of theelongate framework.

Additionally or alternatively, in an eighth example, the covering layerincludes a first portion covering the interconnected struts andinterstices of the elongate framework, and the covering layer includes asecond portion extending across the opening between the first and secondedges of the elongate framework. The first portion has a first thicknessand the second portion has a second thickness different than the firstthickness. In some instances, the second thickness is greater than thefirst thickness, whereas in other instances the second thickness is lessthan the first thickness.

Additionally or alternatively, in a ninth example, the covering layerextends across the opening between the first and second edges of theelongate framework.

Additionally or alternatively, in a tenth example, the covering layerextends across the opening is generally planar.

Additionally or alternatively, in an eleventh example, the endoluminalstent is configured to be implanted in a trachea, and the covering layerextending across the opening is configured to deflect into the lumen ofthe elongate framework during a cough.

Additionally or alternatively, in a twelfth example, the elongateframework has a C-shaped cross section in a plane perpendicular to alongitudinal axis of the elongate framework.

Additionally or alternatively, in a thirteenth example, the C-shapedcross section of the elongate framework includes a first curled endregion, a second curled end region and a central arcuate portion betweenthe first and second curled end regions.

Additionally or alternatively, in a fourteenth example, the first andsecond curled end regions have a radius of curvature less than a radiusof curvature of the central arcuate portion.

What is claimed is:
 1. An endoluminal stent, comprising: an elongateframework including a plurality of interconnected struts extending alonga length of the stent, wherein the elongate framework further includes afirst edge extending along the length of the stent, a second edgeextending along the length of the stent, and an arcuate portionextending between the first edge and the second edge; wherein thearcuate portion includes a concave inner surface; wherein the first edgeincludes a first curled portion, the second edge includes a secondcurled portion, and wherein each of the first curled portion and thesecond curled portion are positioned adjacent to the inner surface. 2.The stent of claim 1, wherein the arcuate portion includes a centralregion, and wherein the first curled portion and the second curledportion are turned inward toward the central region.
 3. The stent ofclaim 1, wherein the concave inner surface extends continuously fromalong the length of the stent.
 4. The stent of claim 1, wherein theelongate framework comprises interconnected struts and intersticesformed therebetween.
 5. The stent of claim 1, wherein the stent isconfigured to be implanted in a trachea, wherein the concave innersurface of the arcuate portion is configured to face the posterior wallof the trachea.
 6. The stent of claim 1, wherein the concave innersurface includes a first radius of curvature, wherein the first curledportion includes a second radius of curvature, wherein the second curledportion includes a third radius of curvature and wherein the secondradius of curvature and third radius of curvature are different than thefirst radius of curvature.
 7. The stent of claim 1, wherein the secondradius of curvature and third radius of curvature are less than thefirst radius of curvature.
 8. The stent of claim 1, wherein the firstand second edge regions are configured to be drawn toward one anotherwith a medical device to remove the stent from a body lumen.
 9. Anendoluminal stent, comprising: an elongate framework; the elongateframework having a first open end, a second open end opposite the firstopen end, and a lumen extending from the first open end to the secondopen end; the elongate framework including a first edge extending fromthe first open end to the second open end, a second edge extending fromthe first open end to the second open end, and an opening between thefirst edge and the second edge, the opening extending continuously fromthe first open end to the second open end; wherein the elongateframework includes a first edge region proximate the first edgeextending from the first open end to the second open end, a second edgeregion proximate the second edge extending from the first open end tothe second open end, and an intermediate region between the first andsecond edge regions extending from the first open end to the second openend; wherein the first edge region includes a first curled end regionand the second edge region includes a second curled end region.
 10. Thestent of claim 9, wherein the intermediate region has a primary radiusof curvature about a primary longitudinal axis extending through thelumen, the first edge region has a first secondary radius of curvatureabout a first secondary longitudinal axis extending through the lumen,and the second edge region has a second secondary radius of curvatureabout a second secondary longitudinal axis extending through the lumen,and wherein the first secondary radius of curvature and the secondsecondary radius of curvature are less than the primary radius ofcurvature.
 11. The endoluminal stent of claim 9, wherein the endoluminalstent is configured to be positioned in a trachea with the first andsecond edge regions oriented toward a posterior wall of the trachea andthe intermediate region oriented toward an anterior wall of the trachea.12. The endoluminal stent of claim 9, wherein the first and second edgeregions are configured to be drawn toward one another with a medicaldevice to remove the endoluminal stent from a body lumen.
 13. Theendoluminal stent of claim 9, wherein the first and second edge regionsare configured to abut one another to resist radial contraction of theendoluminal stent in a body lumen.
 14. An endoluminal stent, comprising:an elongate framework; the elongate framework having a first open end, asecond open end opposite the first open end, and a lumen extending alonga longitudinal axis from the first open end to the second open end;wherein the elongate framework has a C-shaped cross section in a planeperpendicular to the longitudinal axis.
 15. The endoluminal stent ofclaim 14, wherein the elongate framework includes an opening betweenopposing first and second longitudinal edges of the elongate framework,the opening extending continuously from the first open end to the secondopen end.
 16. The endoluminal stent of claim 15, wherein the C-shapedcross section of the elongate framework includes a first curled endregion, a second curled end region and a central arcuate portion betweenthe first and second curled end regions.
 17. The endoluminal stent ofclaim 16, wherein the first and second curled end regions each have aradius of curvature less than a radius of curvature of the centralarcuate portion.
 18. The endoluminal stent of claim 17, wherein thecentral arcuate portion includes a concave inner surface.
 19. Theendoluminal stent of claim 18, wherein the stent is configured to beimplanted in a trachea, wherein the concave inner surface of the arcuateportion is configured to face the posterior wall of the trachea.
 20. Theendoluminal stent of claim 19, wherein the first and second curled edgeregions are configured to be drawn toward one another with a medicaldevice to remove the stent from a body lumen.